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April 24, 2008

Mountain Pine Beetles Producing Tons of Carbon

by Sam Savage

An outbreak of pine beetles is to blame for the destruction of almost 33 million acres of lodgepole pines in British Columbia, resulting in a massive release of carbon equal to five years of emissions from the entire system of Canadian transport.

The findings come from Werner Kurz, a researcher at the Canadian Forest Service. Kurz said he estimates that 990 megatons of carbon dioxide could be released over 21 years of destruction by the pine beetle.

"When trees are killed, they no longer are able to take carbon from the atmosphere. Then when dead trees start to decompose, that releases carbon dioxide into the atmosphere," Kurz said.

The result could cause the forests in British Columbia to release more carbon than it is able to absorb. Some fear that it could hurry the process of climate change, which in fact, is the cause of the beetle outbreak. As warmer temperatures became more prevalent, the beetles were able to survive further north than ever before.

"This is the kind of feedback we're all very worried about in the carbon cycle - a warming planet leading to, in this case, an insect outbreak that increases carbon dioxide into the atmosphere, which can increase warming," said Andy Jacobson, a carbon cycle scientist for the National Oceanic and Atmospheric Administration in Boulder, Colo.

Kurz said that the forest should be able to recover and become an absorption spot for carbon, but he said that even by 2020 it may not be quite as strong as it once was.

"This long-term effect, personally I find it frightening," said Jacobson, who was not involved in the study, which is being published this week in the journal Nature.

"Many other insects also impact the forest carbon cycle," Kurz said. While outbreaks of other insects such as spruce beetles may be much smaller, their cumulative effect is significant, he said.

"If events such as this occur in other geographic parts of the world, then they really ought to be accounted for," Kurz said.